/*
 * Copyright © 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;
using System.Reflection.Emit;
using Spring.Util;

namespace Spring.Aop.Framework.DynamicProxy;

/// <summary>
/// <see cref="Spring.Proxy.IProxyMethodBuilder"/> implementation
/// that delegates method calls to the base method.
/// </summary>
/// <author>Bruno Baia</author>
public class BaseAopProxyMethodBuilder : AbstractAopProxyMethodBuilder
{
    /// <summary>
    /// Creates a new instance of the method builder.
    /// </summary>
    /// <param name="typeBuilder">The type builder to use.</param>
    /// <param name="aopProxyGenerator">
    /// The <see cref="IAopProxyTypeGenerator"/> implementation to use.
    /// </param>
    /// <param name="targetMethods">
    /// The dictionary to cache the list of target
    /// <see cref="System.Reflection.MethodInfo"/>s.
    /// </param>
    /// <param name="onProxyTargetMethods">
    /// The dictionary to cache the list of target
    /// <see cref="System.Reflection.MethodInfo"/>s defined on the proxy.
    /// </param>
    public BaseAopProxyMethodBuilder(
        TypeBuilder typeBuilder, IAopProxyTypeGenerator aopProxyGenerator,
        IDictionary<string, MethodInfo> targetMethods, IDictionary<string, MethodInfo> onProxyTargetMethods)
        : base(typeBuilder, aopProxyGenerator, false, targetMethods, onProxyTargetMethods)
    {
    }

    /// <summary>
    /// Create static field that will cache target method when defined on the proxy.
    /// </summary>
    /// <param name="il">The IL generator to use.</param>
    /// <param name="method">The target method.</param>
    protected override void GenerateOnProxyTargetMethodCacheField(
        ILGenerator il, MethodInfo method)
    {
        if (method.IsVirtual && !method.IsFinal)
        {
            string methodId = GenerateMethodCacheFieldId(method);

            // generate proxy method
            MethodBuilder baseMethod = typeBuilder.DefineMethod("proxy_" + methodId,
                MethodAttributes.Public | MethodAttributes.HideBySig,
                CallingConventions.Standard,
                method.ReturnType, ReflectionUtils.GetParameterTypes(method));

            DefineGenericParameters(baseMethod, method);
            //DefineParameters(baseMethod, method);

            ILGenerator localIL = baseMethod.GetILGenerator();

            localIL.Emit(OpCodes.Ldarg_0);
            // setup parameters for call
            for (int i = 0; i < method.GetParameters().Length; i++)
            {
                localIL.Emit(OpCodes.Ldarg_S, i + 1);
            }

            localIL.EmitCall(OpCodes.Call, method, null);
            localIL.Emit(OpCodes.Ret);

            // create static field that will cache proxy method
            onProxyTargetMethods.Add(methodId, method);

            onProxyTargetMethodCacheField = typeBuilder.DefineField(
                methodId, typeof(MethodInfo), FieldAttributes.Private | FieldAttributes.Static);

            MakeGenericMethod(il, method, onProxyTargetMethodCacheField, genericOnProxyTargetMethod);
        }
    }

    /// <summary>
    /// Calls target method directly.
    /// </summary>
    /// <param name="il">The IL generator to use.</param>
    /// <param name="method">The method to proxy.</param>
    /// <param name="interfaceMethod">
    /// The interface definition of the method, if applicable.
    /// </param>
    protected override void CallDirectProxiedMethod(
        ILGenerator il, MethodInfo method, MethodInfo interfaceMethod)
    {
        CallDirectBaseMethod(il, method);
    }
}
